I thought a could circumvent the alarm by physically locking the car rather than 'blipping' it. But no. The alarm went off a couple of minutes later.
The only way I can figure out how to stop it going off is to leave it unlocked. As you'll understand, that's not entirely satisfactory.

I have a feeling something is wrong as it's stopped flashing when i 'blip' it to lock it. And when I 'blip' it to unlock it, the 2 flashes are further apart than they used to be.
Can I assume from this that the electrics are shot?

I live in the middle of Leeds and leaving it unlocked really isn't an option overnight.

After the last alarm I 'blipped' it and the doors locked but it didn't flash and since then have had no alarm (5 mins or so) - but shall check the doors nonetheless.
If it's not a door issue I should probably assume it's an electrics issue, no?

Thanks for that Marty. If I had the option of it not going off at 2am I would go for that one.
Trust me, living where I do, I get to hear all sorts of alarms at all sorts of times. Which is precisely why I'm wanting to avoid contributing to the cacophony of aural dirt.

If I could buy a car without an alarm right now, I probably would do.

If it continues to go off, I'm going to have to disconnect it somehow. Not being totally clever where these things are concerned, I wouldn't know where the hell to begin.

Lift bonnet and disconnect the battery. The RED + side (Either a spanner or screwdriver will be needed dependant on the battery or can maybe be bodged with a pair of pilers)

then lock doors all doors manually with the key as you won't have any electrics for the central locking etc.

Reconnect battery in the morning.

WARNING: Be careful not to short out the battery with anything metal across the two terminals and take off any metal jewellery and metal watch straps as these can short out the battery and you will end up with nasty burns as they heat up!

My car alarm goes off after about 20 minutes if it's locked and the interior light has been left on. Could this be the issue? On one occasion, shortly after I got the car, it was going off again and again, and it took me ages to work out what it was.

the only time I had a car alarm problem was with my last car (2002 Astra with remote-central locking). While I owned it, the alarm started to go off for no reason. This started to play up within just a couple of days. It was so troublesome that it had to be fixed asap. This is what I learned.

Locking the car manually by turning the key (not using the remote button) doesnt stop the alarm engaging. My current car, a more basic Polo has central locking, but not remote, and it activates the alarm upon turning the key. So this doesnt bypass the alarm.

On the Astra, there were 2 interior light switches. When pressed in a certain order before leaving the car, this would disable the internal cabin motion sensor part of the alarm. But it doesnt disarm the entire alarm. So problem remains.

On the Astra MK4, the alarm has a power backup. Removing the car battery wont stop the alarm!

The Alarm main system is built into the car, so that it cant be removed or taken out. But if it should go wrong......

On that system, the siren part ("Sounder box") is seperate from the rest of the system, which is a good thing, as it was this part that went wrong.

Turns out this is a common failure on Astra's of this age, and the same system maybe used on the MK5 (not 100% sure).

Take care where you leave the car. Even if you leave the car in a locked garage overnight, but the car unlocked to prevent alarm activation, you are not covered by insurance.

A few years ago there was a 'thing' going around - burglars set off car alarms in driveways, hid, people came to their front door, 'blipped' the alarm off and reset it. Burglar does it again, person comes back out, resets it back in.

Burglar does it again, person thinks alarm is knackered with a capital f, so switches it off altogether. Burglar breaks in, steals car/gets stuff from the car and runs...

Is the bonnet right down? My last car, a Focus RS, had a very sensitive alarm and it started to go off when I hadn't secured the bonnet completely - not enough to lift it up when driving but enough to trip the alarm. Took days to solve it.

My car alarm goes off after about 20 minutes if it's locked and the interior light has been left on. Could this be the issue? On one occasion, shortly after I got the car, it was going off again and again, and it took me ages to work out what it was.

Had that with my last car.

It was only about 2 minutes before it went off, though. I'd just parked in a big retail park to go to the cinema, got about 100 metres from the car and heard it go off.

Went back to it two or three times before I figured out that it was the interior light that was still on.

A few years ago there was a 'thing' going around - burglars set off car alarms in driveways, hid, people came to their front door, 'blipped' the alarm off and reset it. Burglar does it again, person comes back out, resets it back in.

Burglar does it again, person thinks alarm is knackered with a capital f, so switches it off altogether. Burglar breaks in, steals car/gets stuff from the car and runs...

I guess it depends on the car, but on the Astra, you couldnt disarm the alarm. Everytime you lock the car, no matter how you lock it, the alarm would always be armed.

If its an Astra (G) it will probably be the power sounder, it has its own power source from batteries inside the sealed unit located behind the wheel arch on passenger side IIRC , the batteries wear out and set the alarm off randomly ,should be around ££120-140 to replace form vxl

I had this with 2 different cars, once it was something to do with the battery ( I had a problem with a connection in the radio which was draining it) and just needed the battery disconnecting and reconnecting again. Second was a fly in the car setting off the sensor alarm, it was driving me mad as it had automatic locks which meant I couldn't leave the car unlocked, I only worked out what it was in the morning when I saw the fly.

BTW, does anyone know if there is a way of disabling the auto locks? It drives me mad if i leave the kids in the car whiole i'm in the petrol garage and stuff and also by the time i've loaded my arms up[ with stuff for the boot etc it's locked itself again.

hi there, iv recently brought a mk 4 astra r reg, its had the standard vauxhall radio in an iv changed it for a cd player, this invold no snipping or anythink jus straight forward swap the plugs over, since doing so my alarm seems to randomly go off as an wen the hell it feels like it an its drivin me nuts let alone the whole street, also my interiour lights have stopped workin also and me nor anytone seems to no how this has happened im havin to leave the car unlocked which is not the best off ideas where i live, can anyone help please,,,ps radio works a treat lol

hi there, iv recently brought a mk 4 astra r reg, its had the standard vauxhall radio in an iv changed it for a cd player, this invold no snipping or anythink jus straight forward swap the plugs over, since doing so my alarm seems to randomly go off as an wen the hell it feels like it an its drivin me nuts let alone the whole street, also my interiour lights have stopped workin also and me nor anytone seems to no how this has happened im havin to leave the car unlocked which is not the best off ideas where i live, can anyone help please,,,ps radio works a treat lol